Pre-patterned substrate layers for being personalized as needed

ABSTRACT

A method and structure for personalizing a multi-layer substrate structure includes supplying a generic layer having electrical features and altering the electrical features to produce a personalized layer of the multi-layer substrate.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention generally relates to multilayer ceramicsubstrates and a method of forming the same.

[0003] 2. Description of the Related Art

[0004] In traditional processing, a substrate contains signal orredistribution layers (which contain connections between differentpoints) and voltage layers which look like mesh planes. Signal orredistribution vias pass through, without connecting to, the mesh plane.To the contrary, voltage vias connect with the mesh planes.Conventionally, each layer is fabricated separately which makes theprocess expensive and time consuming.

[0005] Ceramic packages for supporting semiconductor devices and thelike include ceramic substrates with printed conductive stripesconnected to the device and to input/output pins or other connectionswhich are joined to boards or the like. While many techniques are knownfor forming such ceramic substrates, one of the most popular proceduresfor such fabrication involves the casting of what is termed a ceramicgreensheet, personalizing (i.e., punching and screening) the greensheet,stacking it with other personalized greensheets and subsequentlyprocessing and firing of the stack of ceramic greensheets. The method ofproducing such multilayer ceramic (MLC) substrates for semiconductorpackaging and other electronics applications is well known asillustrated in U.S. Pat. Nos. 4,234,367, 4,302,625 and 4,799,984, eachof which is incorporated herein by reference.

[0006] In the traditional method of building MLC substrates, eachpersonalized greensheet layer has a unique pattern which makes thepersonalization process expensive and time consuming. Accordingly, a newpersonalization process which is less expensive and time consuming isdesired.

[0007] Building multi-layer personalized substrates is expensive andtime consuming. For example, one part of the process involves applyingthe signal patterns to each layer (e.g., each greensheet) beforelamination. A personalized via pattern must be drilled or punched foreach layer as well. A process is needed that would improve the processtime and reduce costs.

SUMMARY OF THE INVENTION

[0008] It is, therefore, an object of the present invention to provide astructure and method for personalizing a multi-layer substrate structurethat includes supplying a generic layer having electrical features andaltering the electrical features to produce a personalized layer of themulti-layer substrate. The altering includes selectively filling vias inthe generic layer with conductive material and removing portions ofelectrical wiring on the generic layer. The process further includessupplying a second generic layer identical to the first generic layerand altering the electrical features of the second generic layer toproduce a second personalized layer different than the firstpersonalized layer. The altering changes the generic layer into aplurality of differently personalized layers. The generic layer includesa grid of vias and/or a pattern of wiring useful with a plurality ofdifferently personalized layers.

[0009] Another embodiment of the invention is a process forpersonalizing a multi-layer substrate structure that includes supplyinga layer having generic electrical features and altering the genericelectrical features to produce a personalized layer of the multi-layersubstrate. The altering includes selectively filling vias in the layerwith conductive material and removing portions of electrical wiring onthe layer. The process further includes supplying a second layeridentical to the first layer and altering the generic electricalfeatures of the second layer to produce a second personalized layerdifferent than the first personalized layer. The altering changes thegeneric layer into a plurality of differently personalized layers. Thelayer includes a generic grid of vias and/or a generic pattern of wiringuseful with a plurality of differently personalized layers.

[0010] Yet another embodiment of the invention is a multi-layersubstrate structure that includes at least one layer having genericelectrical features altered to personalize the layer. The electricalfeatures include vias selectively filled with conductive material and/ora wiring pattern having portions selectively removed. The multi-layersubstrate further includes a second layer similar to the first layer andhaving the generic electrical features altered differently than thefirst layer to personalize the second layer differently from the firstlayer. The layer can be changed into a plurality of differentlypersonalized layers, and it includes a generic grid of vias and/or ageneric pattern of wiring useful with a plurality of differentlypersonalized layers.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The foregoing and other objects, aspects and advantages will bebetter understood from the following detailed description of a preferredembodiment of the invention with reference to the drawings, in which:

[0012]FIG. 1A is a schematic diagram of two layers of a ceramicsubstrate;

[0013]FIG. 1B is a schematic diagram path personalized on a pair ofsheets;

[0014]FIG. 2 is a flowchart representation of the process ofmanufacturing multi-layer substrates.

[0015] FIGS. 3A-3C are schematic cross-sections of a ceramic sheet; and

[0016]FIG. 4 is a perspective view of a ceramic sheet.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0017] The present invention includes a process/structure whichpersonalizes generic signal or redistribution layers by severingconnections and forming conductive vias to create unique product parts.The invention reduces the cost and time associated with multi-layerceramic (MLC) structures because generic electrical features (e.g.,wiring and via patterns) are used for multiple products with differentdesigns. Therefore, the cost associated with forming unique via gridsand screen printing unique wiring or voltage patterns is avoided withthe invention. In other words, with the invention, the same genericwiring and via patterns can be used for many different products bysimply making different vias in the pattern conductive and by severingdifferent connections in the wiring patterns.

[0018] Generally, vias are in certain locations (i.e., grids), andsignal layers contain wiring in only one direction (i.e., X or Y),whereas voltage layers generally contain mesh patterns. One example ofthe invention is the fabrication of voltage or reference layers whichuse a common grid for many different products. The layers arepersonalized for the different products by making certain viasconductive and by severing connections on the layers (e.g., removingportions of the wiring patterns). Currently, in product fabrication suchas multi-layer ceramic greensheet structures, each layer is personalized(e.g., uniquely screen printed, uniquely punched with a via grid).

[0019] In a preferred embodiment, a family of products uses a standardvoltage pattern and each member of the family utilizes a subset of thevias, which have been incorporated for various chip sizes or chipfootprints, to connect to the standard voltage pattern. Therefore, withthe invention, each member of the family takes advantage of the commonvoltage or reference pattern.

[0020] In another embodiment, a common pattern for X, Y orredistribution wiring is made for a given family of products. Each layeris personalized by custom laser deletion of undesired portions of theconductors. This methodology lends itself toward both product specificpersonalization and to customized patterns and provides a means ofrepair when used with patterned surface or subsurface layers.

[0021] Referring now to FIG. 1A, two layers 10, 11 (sheet 1, X wiringand sheet 2, Y wiring) of a ceramic substrate are shown. The layers arepre-drilled with via holes 13 at regular grid locations. Selected vias12 (indicated by large circles) are filled with an insulating materialsuch that they do not make electrical contact between the layers(sheets). The remainder of the vias are filled with conductors and theconductive wiring pattern applied.

[0022] In FIG. 1B, a path is personalized on the pair of sheets byfilling certain vias with conductors and by removing certainconnections. As can be seen in FIG. 1B, the path begins at “A.” A wiresegment is cut at point “B”. A conductive via joins the segments betweensheets 1 and 2 at point “C”. Segment C-D is similarly isolated by cutsand connected to segment E-F with a conductive via. E-F is similarlyconnected to G-H to complete the path A-H. The layers are laminated andother layers are similarly personalized and laminated to form the MLCsubstrate.

[0023] Referring now to FIG. 2, a flowchart illustrating an embodimentof the invention is shown. In item 20 of the flowchart, a standard(e.g., generic) array of via holes 13 are formed in a sheet 10. Then, initem 21, selected ones of the vias 12 are filled with a non-conductivematerial. Then, as shown in item 22, a standard (e.g., generic) patternof conductive wiring is applied and the remaining via holes are filledwith a conductive paste. As shown in FIG. 1B, selected locations of thegeneric wiring pattern are cut (item 23) to personalize the sheet. Then,the vias of sheet 10 are aligned with those of sheet 11, as shown initem 24. Finally, in item 25 sheet 10 is laminated to sheet 11.

[0024] In the process described above, any conventional method can beused to selectively fill the vias with a conductor or insulator, asshown in FIG. 3A, to personalize the otherwise generic sheet. Alsoillustrated in FIG. 3A are the cuts 30 in the generic wiring pattern 31which personalize the sheet. For example, a stencil, mask or othersimilar device can be used to selectively fill the vias with aninsulator or conductor using any well known screening process.Similarly, the electrical wiring connections 31 can be cut 30 using anywell known process, such as laser cutting, physical cutting, etching,sand blasting, punching, electrically blowing links, grinding, etc.Alternatively, as illustrated in FIG. 3B, all the vias are filled with aconductor 13 and insulating caps 32 are formed over selected ones of theconductors 13 to personalize of the sheet. As would be known by oneordinarily skilled in the art given this disclosure, the caps 32 can beformed in any conventional process, such as screening and other similarprocesses.

[0025] Referring to FIG. 3C, all wiring (X or Y) layers, 11, have allvias filled with conductive paste. In order to connect only selectedvias between two layers, an interposer layer 40 is used with theselected vias, 42 (filled with conductive paste) and the other(nonconducting) vias, 41, are left empty. Connections between successivelayers are made through selected vias. Sheet 40 may be of differentthickness to maintain overall substrate thickness. This method offersseveral advantages: first a common punch pattern could be used for alllayers, second only simple through via masks are required for interposerlayers and third, no insulating (nonconductive) paste screening isrequired.

[0026] Referring to FIG. 4, lines are screened such that connections toall of the vias are made. Each layer is personalized based on the designrequirements. Connections to vias, 33, that are not supposed to beconnected are removed using methods such as laser ablation, e-beam,sandblasting, etc. Advantages of this method include use of common punchand screen pattern and elimination of need for screening with insulatingpaste.

[0027] Thus, as described above, the invention uses common genericpre-drilled/pre-wired substrate sheets that are personalized using cuts(e.g., laser) and selective conductive via fills, as needed. While a viainterconnect system is described in the preferred embodiment above, aswould be known by one ordinarily skilled in the art given thisdisclosure, other similar processing is possible with the invention. Forexample, an insulator may be placed against those vias that are not tobe conductive thru vias as shown in FIG. 3B.

[0028] The invention allows for quicker build times for new products anda reduction of punched sheet part numbers, which results in larger batchsize and reduced costs. It is ideal for gang punching of a product.Minimal screening masks would be required.

[0029] While the invention has been described in terms of preferredembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theappended claims.

What is claimed is:
 1. A process for personalizing a multi-layersubstrate structure comprising: supplying a generic layer havingelectrical features; and altering said electrical features to produce apersonalized layer of said multi-layer substrate.
 2. The process inclaim 1, wherein said altering comprises selectively filling vias insaid generic layer with conductive material.
 3. The process in claim 1,wherein said altering comprises removing portions of electrical wiringon said generic layer.
 4. The process in claim 1, further comprisingsupplying a second generic layer identical to said generic layer andaltering said electrical features of said second generic layer toproduce a second personalized layer different than said personalizedlayer.
 5. The process in claim 1, wherein said altering changes saidgeneric layer into a plurality of differently personalized layers. 6.The process in claim 1, wherein said generic layer includes a grid ofvias useful with a plurality of differently personalized layers.
 7. Theprocess in claim 1, wherein said generic layer includes a pattern ofwiring useful with a plurality of differently personalized layers. 8.The process in claim 1, wherein said altering comprises selectivelyfilling vias in said generic layer with an insulating material.
 9. Theprocess in claim 1, wherein said altering comprises selectively forminginsulating caps adjacent selected ones of conductive vias in saidgeneric layer to render said selected ones of said conductive viasnon-conductive.
 10. The process in claim 9, wherein said forming of saidinsulating caps comprises screening a insulating paste.
 11. The processin claim 9, wherein said forming of said insulating caps comprisesplacing dry insulating material over said selected ones of saidconductive vias.
 12. A process for personalizing a multi-layer substratestructure comprising: supplying a layer having generic electricalfeatures; and altering said generic electrical features to produce apersonalized layer of said multi-layer substrate.
 13. The process inclaim 12, wherein said altering comprises selectively filling vias insaid layer with conductive material.
 14. The process in claim 12,wherein said altering comprises removing portions of electrical wiringon said layer.
 15. The process in claim 12, further comprising supplyinga second layer identical to said layer and altering said genericelectrical features of said second layer to produce a secondpersonalized layer different than said personalized layer.
 16. Theprocess in claim 12, wherein said altering changes said layer into aplurality of differently personalized layers.
 17. The process in claim12, wherein said layer includes a generic grid of vias useful with aplurality of differently personalized layers.
 18. The process in claim12, wherein said layer includes a generic pattern of wiring useful witha plurality of differently personalized layers.
 19. A multi-layersubstrate structure comprising: at least one layer having genericelectrical features altered to personalize said layer.
 20. Themulti-layer substrate structure in claim 19, wherein said electricalfeatures include vias selectively filled with conductive material. 21.The multi-layer substrate structure in claim 19, wherein said electricalfeatures include a wiring pattern having portions selectively removed.22. The multi-layer substrate structure in claim 19, further comprisinga second layer similar to said layer and having said generic electricalfeatures altered differently than said layer to personalize said secondlayer differently than said layer.
 23. The multi-layer substratestructure in claim 19, wherein said layer is for being changes into aplurality of differently personalized layers.
 24. The multi-layersubstrate structure in claim 19, wherein said layer includes a genericgrid of vias useful with a plurality of differently personalized layers.25. The multi-layer substrate structure in claim 19, wherein said layerincludes a generic pattern of wiring useful with a plurality ofdifferently personalized layers.
 26. The multi-layer substrate structurein claim 19, further comprising: conductive vias; and insulating capsadjacent selected ones of said conductive vias, wherein said insulatingcaps render said selected ones of said conductive vias non-conductive.27. The multi-layer substrate structure in claim 27, wherein saidinsulating caps comprise a screened insulating paste.
 28. Themulti-layer substrate structure in claim 27, wherein said insulatingcaps comprise a dry insulating material.